A university psychiatrist was so alarmed by cinema massacre suspect James Holmes' behaviour that she tried to bring him to the attention of the school's threat assessment team, reports said.
Dr Lynne Fenton voiced alarm more than a month before the deadly attack in Aurora, Colorado, but the group never met to talk about Holmes because he had already taken steps to drop out, a Denver TV station said.
Holmes, 24, is charged with murdering 12 people and wounding 58 in the July 20 rampage at a midnight premiere of the new Batman film The Dark Knight Rises, near the Aurora campus, after methodically stockpiling guns and ammunition for months.
In the wake of the Virginia Tech tragedy five years ago - the deadliest shooting in American history - the University of Colorado and other schools across the US created threat assessment teams to identify and take action against students who might turn violent.
Now, in the aftermath of the rampage in Aurora, some are wondering whether the system broke down. "If the argument is because he was no longer a student, he was no longer their problem, they are absolutely incorrect," said Larry Barton, a threat consultant and professor at American College in Pennsylvania. "Any court and any victim's family would have an argument that the school acted with indifference. I hope they have a very compelling answer to why they did what they did."
University chancellor Don Elliman has repeatedly said the school did all it could with regard to Holmes. He and other university officials have refused to discuss any specifics, citing privacy laws and a judge's gag order.
The university would not say whether staff members had any concerns about Holmes or whether police were ever alerted to him. However, KMGH-TV and the Denver Post, citing unidentified sources, said police were never contacted.
It's not clear what alarmed Dr Fenton, or whether she even treated Holmes. But she helped found the school's Behavioural Evaluation and Threat Assessment Team in 2010.
Even if the Colorado team had convened and police investigated, it is unclear whether any violence could have been prevented. In December, Morgan State University police and counsellors in Baltimore evaluated student Alex Kinyua following an outburst in a computer lab and concluded he posed no threat. Months later he was charged with murdering a man and eating his heart and brain.
And in Arizona, Pima Community College student Jared Loughner had several run-ins with faculty members, students and campus police before he was suspended in 2010. Campus police told him to get a mental health evaluation or not return. Loughner was later arrested in the 2011 assassination attempt against congresswoman Gabrielle Giffords that left six people dead.